Calibre on 20.04 will not launch due to python issues.

[Bill (franksmcb)]

Calibre will not launch in 20.04.

Running from the CLI:

$ calibre
Traceback (most recent call last):
  File "/usr/bin/calibre", line 20, in <module>
    sys.exit(calibre())
  File "/usr/lib/calibre/calibre/gui_launch.py", line 73, in calibre
    main(args)
  File "/usr/lib/calibre/calibre/gui2/main.py", line 543, in main
    listener = create_listener()
  File "/usr/lib/calibre/calibre/gui2/main.py", line 514, in create_listener
    return Listener(address=gui_socket_address())
  File "/usr/lib/calibre/calibre/utils/ipc/server.py", line 110, in __init__
    self._listener._unlink.cancel()
AttributeError: 'NoneType' object has no attribute 'cancel'

This was reported by a Ubuntu MATE user.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: calibre 4.99.4+dfsg+really4.12.0-1build1
ProcVersionSignature: Ubuntu 5.4.0-48.52-generic 5.4.60
Uname: Linux 5.4.0-48-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.9
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: MATE
Date: Wed Oct 14 14:58:57 2020
InstallationDate: Installed on 2020-09-18 (25 days ago)
InstallationMedia: Ubuntu-MATE 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: calibre
UpgradeStatus: No upgrade log present (probably fresh install)

[Bill (franksmcb) (franksmcb)]

Please see exchange from ubuntu-devel mailing list:

Date: Wed, 14 Oct 2020 09:06:35 +0900
From: Norbert Preining <email address hidden>
To: <email address hidden>
Cc: Eli Schwartz <email address hidden>
Subject: Ubuntu Focal update of broken Calibre package
Message-ID: <email address hidden>
Content-Type: text/plain; charset=us-ascii

Dear all,

(please Cc)

I am the Debian maintainer of Calibre, and unfortunately it seems that
for Focal Ubuntu has pulled a preliminary version of Calibre, which is
**seriously** broken and unusable, not even starting in most cases.

We were forced by the Python3 transition to temporarily ship pre-release
versions of Calibre. In particular, Ubuntu Focal ships
 4.99.4+dfsg+really4.12.0-1build1
which is version 4.12 with experimental Python3 patches on top of it.
This worked for a short time being until Calibre 5 was released with
proper Python3 support.

Due to this unfortunate squeeze in release timing, Ubuntu Focal users
now have a seriously broken Calibre, and upstream is swamped with bug
reports.

I would strongly suggest and support, and help preparing, an update to
Focal based on the current version in Debian/testing, 5.2.0+dfsg-1,
which has been out since quite some time and field-tested with Python3
in various environments, due to upstream having switched to Py3, too.

Is the above (update to 5.2.0) possible in Ubuntu Focal, and if yes,
what kind if steps are necessary?

Note that I am not an Ubuntu developers, but Debian developer and
maintainer of Calibre.

Thanks and all the best

Norbert

Date: Wed, 14 Oct 2020 12:45:40 +0200
From: Lukasz Zemczak <email address hidden>
To: Norbert Preining <email address hidden>
Cc: ubuntu-devel <email address hidden>, Eli Schwartz
 <email address hidden>
Subject: Re: Ubuntu Focal update of broken Calibre package
Message-ID:
 <email address hidden>
Content-Type: text/plain; charset="UTF-8"

Hello Norbert,

With my SRU team hat on, after reading what you said about the status
of current calibre, I would say it is possible to update the package
version in focal to 5.2.0. But we would need to know a bit more, and
there is some (important) paperwork to do.

First thing to remember is that for a new version to be releasable to
a stable series it also has to be present in all the newer series as
well - so groovy upwards. We are long past debian import freeze so
groovy is still on 4.99.12+dfsg+really4.23.0-1 - and syncing 5.2.0
now, so late in the cycle, requires an approved Feature Freeze
Exception [1], since we're also past feature freeze. It's a very very
unfortunate time, since Final Freeze for groovy is tomorrow, and we're
a bit reluctant with accepting risky pieces. The 'good' news is,
calibre is only seeded in our Ubuntu Studio flavor, so the impact
should be manageable. I would like the Ubuntu Studio flavor
representatives to chip in and (maybe) help out with the paperwork
there.

Once we have it in groovy+ we can look into backporting it to focal.
This requires filling in some SRU paperwork as per the policy [2].
What makes it a bit problematic from the SRU perspe...